Reluctant to ignore learner's swear-word (4)
I believe the answer is:
oath
'swear-word' is the definition.
(I've seen this before)
'reluctant to ignore learner's' is the wordplay.
'reluctant' becomes 'loath' ('loath' can be a synonym of 'reluctant').
'to ignore' indicates named letters should be taken away.
'learner' becomes 'l'.
'loath' with 'l' taken out is 'OATH'.
(Other definitions for oath that I've seen before include "Commitment to tell the truth" , "'Profane, or solemn expression (4)'" , "Vow or expletive" , "Sworn promise" , "Vow, sworn word" .)